Various types of carpet padding are used between flooring and decorative carpet to provide cushioning and support to the overlying carpet, thereby improving the stability and life of the carpet. A typical single layer pad is formed of re-bonded foam particles. Over a period of use, however, the foam particles crumble and the bond between the foam particles weakens, thereby causing the padding to lose its cushioning and support characteristics. Other single layer pads are comprised of natural or synthetic fibers, or a combination thereof, which are mechanically or adhesively bonded together. While sturdier, the fibers tend to separate over a period of wear, thereby causing the fiber padding to break down.
While single layer pads are generally proposed for use as carpet padding, it is also known in the art to use multi-layer padding. As described in U.S. Pat. No. 5,762,735 to Collins et al., a polymeric foam layer is sandwiched between, and bonded to, a liner sheet and a preformed layer of foam. The liner sheet is a layer of low density polyethylene, the polymeric foam layer is polyurethane and the preformed padding material is comprised of foam materials such as polyurethane form or re-bonded particle foam padding. Another multi-layer carpet pad comprising a liner sheet of polyethylene, two polyurethane foam layers and a second polyethylene liner sheet is described in U.S. Pat. No. 5,846,461 to Collins et al. Other multi-layer carpet pads are described in U.S. Pat. No. 5,531,849 to Collins et al. for a polyurethane layer sandwiched between two layers of polyethylene liner and in U.S. Pat. No. 5,045,389 to Campagna for a top layer of polyethylene, an intermediate layer of polyurethane foam and a base layer of rebonded polyurethane foam.
Processes for forming multi-layer carpet pads are described in the Collins et al. '735, '461 and '849 patents. For example, the Collins et al. '735 patent describes a process for making a laminated carpet pad by feeding a polyethylene liner sheet onto a conveyor belt and spraying thereon polyurethane foam which is uncured. Preformed foam padding is applied to the uncured polyurethane foam. The composite pad is fed between a pair of heated conveyor belts to cure the polyurethane foam and to adhere the foam to the liner sheet and the foam padding.
The Collins et al. '461 patent describes a process for making a laminated carpet pad by feeding a first liner sheet of cured polyurethane foam material and a polyethylene layer onto a conveyor belt. Uncured polyurethane foam is sprayed onto the cured polyurethane foam layer. A second liner sheet is applied to the uncured polyurethane foam to sandwich the polyurethane foam between the first and second liner sheets. The composite is fed between a pair of heated conveyor belts to cure the polyurethane foam and to adhere the foam to the first and second liner sheets.
The Collins et al. '849 patent describes a process for making a carpet pad by feeding a first polyethylene sheet onto a conveyor belt and spraying uncured polyurethane foam thereon. A second polyethylene liner sheet is applied to the uncured polyurethane foam. The composite pad is fed between a pair of heated conveyor belts to cure the polyurethane foam and to adhere the foam to the first and second liner sheets.